Does the editor Symbol field supposed to work with all the unit Types or only Infantry?

I have 2 light horse regiments that I want to show up with the cavalry symbol so I put 12 in the Symbol field. I want them to move fast so they are Armor Unit Type. But they show up with the armor symbol even when I put 12 the Symbol field.

I changed one of them to an Infantry Unit Type, and then the cavalry symbol shows up ok. The second one is still an Armored Unit Type and shows up with the armor symbol even with 12 in the box.

Is this right, the special symbols only work for Infantry Unit types? Not complaining, just curious if it is WAD. Sam